Generation of focused, nonspherically decaying pulses of electromagnetic radiation

Periodic pulses of polarized electromagnetic radiation can be generated whose intensity diminishes with the distance R-p from their source like R-P(-1) instead or R-P(-2). The source required Is an extended charge with a rotating distribution pattern whose outer parts move with linear phase speeds exceeding the speed of light in vacuo. The coherence and beaming of the radiation in question stem from constructive interference of the emitted waves and formation of caustics. These processes take place at different distances from the source for different sets of waves, so that the propagating wave packets embodying the pulses are constantly dispersed and reconstructed out of other waves. [S1063-651X(98)05211-8].